With the processing speed of the central processing unit (CPU) of the computer increasing constantly, heat energy generated by the CPU during operation also increases tremendously. In the past, CPU cooling was overlooked. As a result, the CPU generates a lot of heat energy and operates at high temperature. Not only the performance of the CPU suffers, its life span also shortens.
At present the general approach to resolve this problem is to add a radiator in contact with the CPU. The heat energy of the CPU transfers to the radiator, and the radiator has radiation fins to dissipate the heat energy. Heat may be transferred by conduction, convection and dissipation, and the radiator mentioned above dispels heat from the CPU by conduction. Namely a solid substance is used as a medium of heat transfer to dissipate heat. Conductive heat transfer is faster than other heat transfer methods. This is because the electrons of the medium molecules that have absorbed enough heat energy jump to a higher energy level and hit the electrons of the neighboring medium molecules. Further, the heat energy is transferred to the neighboring medium molecules, while the electrons that release the heat energy return to a lower energy level. Therefore, the heat energy may be transferred and dispelled.
The radiator generally has two types: one has dissipation fans, and the other does not have the dissipation fans. The radiator with a dissipation fan can generate cooling airflow to the radiation fins to increase cooling speed of the convection. It uses fluid as a heat transfer medium to dispel heat. It generally has a better cooling efficiency than the radiator without the dissipation fans.
On the heat dissipation methods for the CPU set forth above, the radiator is a solid substance, while the air is a fluid one. The distance between the medium molecules of the radiator is shorter that that of the air molecules. Most radiators are made of metal, and have more free electrons to transfer heat energy (because the medium molecules are confined in crystal lattice and cannot move). Hence heat transfer by conduction is faster than by convection.
However, in order to improve the performance of the dissipation fan, the dissipation fan usually is installed close to the radiator. Some even are mounted on one side or the top end of the radiator. This approach adds a heavy load to the CPU and increases the damage probability of the CPU.
Some conventional radiators alter the design of radiation fins or change the material of the radiation fins to improve cooling efficiency.